Remember our “indoors” is a delicate ecosystem as we’ve discussed in other blog posts. Buildings must be kept clean and dry because buildings actually breathe. In the IAQ world there’s an old joke that buildings shouldn’t suck, they blow. Meaning indoor spaces function best when held under a bit of positive pressure. This helps to dilute contaminants and ventilate them to non-inhabited “voids” in the building, or to the outdoors.